Applied Mechanics and Materials Vols. 268-270

Abstract: The emulsion polymerization of methyl methacrylate (MMA) with butyl acrylate (BA) using aqueous polyurethane dispersion as seed was undertaken to prepare acrylic-polyurethane (PUA) hybrid emulsions with high solid content. The concentrations of the anionic groups were varied by adding different amount of dimethylolpropionic acid (DMPA). The emulsions with a similar bimodal particle size distribution (PSD) were obtained. The viscosity of the emulsions is about 350 mPa^.s while the solid content is about 55%.

Abstract: Poly(3-methoxythiophene)/NiO (PMOT/NiO) composite films were electrochemically synthesized on a ITO surface in the ionic liquid 1-butyl-3-metyllimidazolium hexafluorophosphate ([BMIM]PF6) by a potentiodynamic polymerization method. The PMOT/NiO composite films were characterized by energy-dispersive X-ray analysis(EDS) and scanning electron microscopy (SEM). Electrochemistry properties of the prepared film was characterized by cyclic voltammetry. Spectroelectrochemistry and electrochromic properties of the PMOT/NiO composite were characterized using various experiment techniques in [BMIM]PF6.

Abstract: To obtain a kind of composite particles material which has the property of both fly ash glass beads (FA) and titanium dioxide (TD), chemical hydrolysis precipitation method was adopted. Each process condition was investigated and the results were characterized by titanyl sulfate hydrolysis rate and the effect of FA coated TD. Composite structure and properties were characterized by means of X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and testing physical properties of FA/TD. The results show that the surface of FA has been coated with TD uniformly and compactly after titanyl sulfate hydrolysis and cladding content roasted. The optimal preparation conditions are hydrolysis cladding temperature 100°C, time 180min, matrix slurry concentration 0.5%, titanyl sulfate solution dosage 0.5g/g and titanyl sulfate solution drop way for the graded way. The hiding power and whiteness of the composite powder are respectively 35.47 g/m2 and 54.43. The results also show that the composite powder has similar pigment performances with TD and it is much whiter than material.

Abstract: Al2O3-SiO2-ZrO2 composite sol was prepared with aluminum nitrate, zirconium oxy-chloride, etc as precursors, by which Al2O3-SiO2-ZrO2 composite ceramic microfiltration membrane was achieved. Stable boehmite sol can be obtained by adding Al(NO3)3 into ammonia but not the reverse. The stability of the composite sol depends on the ratio of Si/Zr. The aperture of the composite membrane can be micron level. It has good effect on sewage treatment.

Abstract: C/C-SiC brake composites, based on reinforcement of carbon fiber and dual matrix of carbon and silicon carbide, were fabricated by warm compacted-in situ reacted process. Rules about the influence of different components on the friction and wear characteristics of the C/C-SiC composites are ascertained. As hard particle, the SiC has the function to the formation of friction film, which is in favor of increasing the coefficient of friction (COF) and decreasing the wear rate. The resin carbon plays the role of enhancing the COF, but they are easy to be cut and increase the wear rate. The graphite plays the lubrication function, and right volume content of graphite is helpful to forming friction film to reduce the wear rate. The C/C-SiC composite fabricated by the warm compacted-in situ reaction can with best tribological performance when the components volume fraction of carbon fibre, SiC, graphite and resin carbon are 15.5%, 37.0%, 22.1% and 20.8%, respectively, which the COF and the wear rate can reach the maximum and the minimun value of 0.44 and 1.1μm/cycle respectively.

Abstract: This paper presents the structural, ferroelectric, ferromagnetic, resonance and magnetoelectric (ME) properties of multilayered ME composites fabricated using molten-salt synthesis method. The compositions corresponding to CoFe2O4 (CFO) with particle size of ~ 150 nm and Ba0.8Sr0.2TiO3 (BST) with particle size of ~ 100 nm were chosen as ferromagnetic and ferroelectric phases. The largest direct magnetoelectric (DME) and converse magnetoelectric (CME) coefficients of the multilayered ME composite were, respectively, 36 μV/cm•Oe at a bias magnetic field of 2800 Oe and 1.16×10-3G/V at a frequency of 30 kHz. In addition, the corresponding interfacial coupling coefficient was calculated to be 3.2×10-5. For the multilayered ME composite, the resonance frequency of 4.97 MHz and bandwidth of 30 kHz were obtained using capacitance-frequency spectrum method.

Abstract: Dynamic mechanical behaviors are critical to the engineering applications of hollow spheres filled syntactic foams. The potential of such composites cannot be fully realized unless the effects of strain rate on their mechanical properties are fully understood. In this study, both the compressive and the tensile behaviors of an epoxy syntactic foam filled by ceramic microspheres were experimentally investigated over the strain rate range from 0.001 to 2000 s-1. The compressive and tensile tests at high strain rates were carried out by means of split Hopkinson pressure bar (SHPB) and split Hopkinson tensile bar (SHTB), respectively. The stress-strain responses and failure mechanisms were examined quantitatively and qualitatively. The experimental results indicate that both the compressive and the tensile behaviors of syntactic foam are highly sensitive to strain rate. Moreover, a comparison of the stress-strain curves suggests that the compressive and tensile behaviors are dominated by different failure mechanisms, which consequently lead to distinct effects of strain rate on the compressive and tensile behaviors of syntactic foam.

Abstract: Experimental investigations were performed on strain characteristic of filament wound composite pipes. Pipes were wound with S-1 glass fiber and epoxy resin, and then subjected to axial tension. Three kind of winding pattern were adopted. The displacement-Load data were recorded. The process of failure was analyzed and functional failure was defined. Based on experimental result of three kind of winding pattern, the effect of winding pattern on axial limited load was presented. There is apparently influence on pipes axial limited load caused by winding pattern.

Abstract: The effects of Si3N4 addition on the room temperature physical properties and hot modulus of rupture(HMOR) of unfired A12O3-C slide plate were investigated by using tabular corundum and reactive alumina as starting materials, aluminium powder and silicon powder as antioxidation agents, phenolic resin as binder. The phase composition and microstructure was characterized by X-Ray diffraction (XRD), scanning electron microscope (SEM), and EDAX. The results showed that with addition of Si3N4, the compactness of A12O3-C slide plate decreased, the room temperature strength deduced. Due to formed cylindrical sialon as a binder phase, the hot modulus of rupture increased.

Abstract: This paper is to explore the feasibility of TiN/Cu-based composite materials as electrical discharge machining (EDM) electrodes.The tool wear ratio (TWR) of EDM electrode directly reflects the machining precision. To reduce the tool wear ratio(TWR) of Cu electrode in the EDM processing, Inorganic mixture of different content of ceramic materials TiN powder and Cu powder are prepared , then pressed and sintered into EDM electrodes.Experimental results show that: in the six batchs of experiments, the tool wear ratio (TWR) of 35%TiN/Cu electrode is the least, which is about 4.98%, much less than that of commercial copper electrode . The microstructures of the TiN/Cu electrodes after electrical discharge machining (EDM) as well are analyzed in this paper.